The US tested a lot of planes for float versions, but the evolving ability to get land bases up and going quickly scotched the proposals. It's also a major reason the USN started using Liberators and Venturas and standardized on the PBY-5A. The game should terminate PBY-5 production at the end of 1942 and just provide PBY-5As from then on. Same number of airframes, just more -5As.

It's easier to maintain land based aircraft than seaplanes and a base supporting only land planes is more efficient than supporting both types.